[Dev] Existing p2p systems for getting offline node back up to date?

Ray Ryan ray.ryan at pobox.com
Thu Nov 14 10:26:39 PST 2002


On Wednesday, November 13, 2002, at 08:20  PM, Mike C. Fletcher wrote:

> I may be mistaken, but don't distributed hashtables try to keep the 
> messages pressed into them for as long as possible w/out regard to 
> their delivery status? That is, rather than being able to retire an 
> item when it reaches it's recipient, the engine is trying to store a 
> document for as long as possible, but normally can't give any 
> guarantee that anyone has accessed it before it is dropped?

Which seems reasonable.

I'd expect that, once a node has left a Chandler group, the rest of the 
group forgets it ever existed. If every node has to remember every 
other node that it may eventually come into contact with again...that 
doesn't seem practical.

I imagine it like this:

A node wakes up and looks around for an existing Chandler pool. It 
finds one and asks an arbitrary member for the status of each 
"document" the new node subscribes to.

For each document that is actually known by the pool, the new node 
absorbs whatever changes it has missed. At the same time, it announces 
any offline changes that the pool has never heard of. Once this syncing 
is accomplished, the new node is a full fledged peer.

The point is that no one has been storing up any delayed messages for 
the returning node while it has been away, or even remembers that it 
once existed.

Now I'm very naive in this space. I have no idea if tools like this 
exist already, especially in the Open Source arena. I'd never even 
heard of distributed hash tables before joining this list (worth the 
price of admission right there!). But this is the tool that I'd love to 
have.

Ray




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